The present invention relates to technical and functional enhancements especially created to characterise the means that significantly improve the use and the functioning of liquid containers. For this purpose, this invention defines an air vent or communicating means of an air inlet, adaptable to liquid containers whose body may be rigid, quasi-rigid or flexible, whereby the function of such an air vent aims at avoiding the formation of vacuum at the bottom of the container at the beginning, and during the discharge of liquid; logically, the neutralisation of the vacuum is obtained by the fact that the above mentioned air vent enables external air to be sent directly to the bottom of the container before the beginning of the discharge or of the liquid suction; and, this air flow does not even go through the liquid discharged, which thus provides different technical effects that are beneficial for the functioning of the entire set.
These properties are attained through using the principle of communicating vessels, balancing pressures, and building an adequate container project. The principle of communicating vessel establishes that: “The levels of liquid in two adjacent vessels are equal since the pressures on those levels are equal”. So, when, two adjacent vessels have their tops open to atmosphere their levels are equal. When we tilt the vessels the levels inside of them will stay still and horizontal. Above certain angle, the liquid of the vessel which is in the upper position will flow to the vessel which is in the lower position. However, when one of the vessels (container body) has a lid with a spout/nipple and the other vessel (air vent tube) is open or close to atmosphere, it will be necessary that the container body and air vent tube have some characteristics to behave like the two adjacent vessels open to atmosphere, that is, to function according to the principle of communicating vessels, when they are tilted.
In almost all containers, the liquid outlet creates a vacuum at the bottom of the container, thereby requiring that external air go down to the bottom of the container so as to break the aforesaid vacuum and allows for a flow to occur.
In most cases, external air enters through the own discharge system or through an orifice in the closest outlets, and goes through the entire liquid before reaching the bottom of the container; an example of this: olive oil cans, cleaning product containers, some types of baby bottles, etc. In those cases, the flow is usually not uniform (gushes), and very often the container is also pressed to improve the outlet flow; however, this very often ends up making the product come out in an excess through the spout and the product may also come out through the air vent just like in olive oil containers, for instance.
There currently are some solutions enabling that an amount of air is introduced inside the container as the liquid comes out. Those solutions are used in baby bottles and other devices or containers. The research conducted came across some instructional documentation on the different solutions for the same problem, among which we may specify: U.S. Pat. No. 189,691 dated Apr. 17, 1876; U.S. Pat. No. 345,518 dated Jul. 13, 1886; U.S. Pat. No. 598,231 dated Feb. 1, 1898; U.S. Pat. No. 679,144 dated Jul. 23, 1901; U.S. Pat. No. 834,014 dated Oct. 23, 1909; U.S. Pat. No. 979,607 dated Dec. 27, 1910; U.S. Pat. No. 1,600,804 dated Sep. 21, 1926; U.S. Pat. No. 2,239,275 dated Apr. 22, 1941; U.S. Pat. No. 2,742,168 dated Apr. 17, 1956; U.S. Pat. No. 2,744,646 dated May 8, 1956; U.S. Pat. No. 5,284,261 dated Feb. 8, 1994; U.S. Pat. No. 5,692,627 dated Dec. 2, 1997; and U.S. Pat. No. 6,138,710 dated Oct. 31, 2000
In the above mentioned documents, and in the products currently marketed, many containers, including baby bottles in general, have different means to allow for the inlet of external air just as the liquid is discharged outwards. In many cases, the air vents are located on the lid of the container. As an example, we may refer to some olive oil containers, whose lid or cap has a device (valve) with a little tube which discharges the air into the liquid so that it cannot do any other than go through the liquid down to the bottom of the container, as the small tube does not go to the bottom of the container (where there is only air).
On the other hand, according to some of the above mentioned literature, baby bottles as well as some types currently manufactured make the air go to the bottom of the bottle in different manners, all of which aim at improving the drainage or outflow of the liquid.
For some traditional baby bottles, external air enters through the very hole of the nipple, or through orifices around the nipple, or even through apertures of the lid, or of the screw thread of the lid; the liquid then goes down to the bottom of the baby bottle. In those cases, the baby swallows the air along with the milk, which triggers off a series of consequences such as colic, gas, and other symptoms.
Some types of baby bottles have an air inlet at the bottom part, where various constructive details contribute to forming a kind of valve made of a combination of various apertures in a membrane assembled at the bottom of the bottle and fixed with a lid similar to that for the nipple; thus, as the bottle is turned downwards to start liquid suction, a certain amount of air enters through the membranous valve to eliminate the vacuum formed at the bottom of the bottle. This system undoubtedly improves the functioning of the baby bottle significantly; however, its industrial feasibility is complex and generates a substantial increase of the manufacturing cost, since the functioning ends up being equally as complex and requiring special cleaning care, besides the fact that the parts are disposable (membrane).
Another type of baby bottle has an air vent assembly formed by a small reservoir inside and coaxial to the bottle, which is connected to external air through an insert, which has an air vent tube, through which external air goes down through the reservoir, to the bottom of the bottle, without ever being in contact with the milk after the initial vacuum is gotten rid of. When the baby bottle is tilted the milk flows to the wider part of the reservoir and do not leak due to the insert. Although this type of baby bottle is constructed in a particular way and functions excellently, it requires a series of special care; in other words: it does not enable any sudden changes in handling (shaking, etc. . . . ) since in that case and in other similar ones leakage may occur through the air vent; the air is only sent to the bottom of the bottle after the baby starts sucking so that the vacuums forms at the bottom of the bottle and therefore, at the beginning, the milk located in the tube goes to the bottom of the bottle; also this type of air vent does not allow for the bottle to be warmed up in a bain-marie.
Finally, there is also a type of baby bottle whereby the air vent system or device that neutralizes the vacuum is formed by a flexible and disposable case, placed inside the bottle. Besides containing all the liquid, this case works as a pressing tank, that is, a kind of piston presses on the abovementioned case as the liquid goes out; this stops the formation of a vacuum as the aforesaid case changes shape, thereby no longer requiring air to enter inside.
In brief, the analysis of the above containers and other usual containers, shows that none of them has an air vent like the air vent tube proposed in this work, whose functioning is based on the principle of communicating vessels.
We should point out that two cases have been considered in this work. In the first case the external air will be at the container bottom, before the outflow is even started, it will not cross the liquid inside the container and there will not be vacuum at the beginning or during the outflow. In the second case, depending on the type of the usual container, it may fulfil the principle of communicating vessel, as in the above case, or it will not fulfil completely the above principle. Even in this last case the external air will also go down to the bottom of the container without crossing the liquid and there will not be vacuum during the outflow of the liquid.